1. Animal studies have shown that arterial baroreflexes are modulated by reflexes originating from the cardiopulmonary volume receptors, and that this modulation consists of a reduction of the inhibitory influence exerted by arterial baroreceptors on the heart and peripheral circulation. This has not been confirmed in man, however, in whom no reduction in the bradycardic response to carotid baroreceptor stimulation has been observed after the mild increase in central venous pressure (right atrial catheter) and cardiopulmonary receptor activity provided by passive leg raising.. 2. In seven normotensive subjects carotid baroreceptors were gradedly stimulated by progressively increasing carotid transmural pressure through a neck chamber device, the resulting reflex lengthening in R-R interval being measured in the two-three cardiac cycles immediately after the baroreceptor stimulus. This manoeuvre was performed in control conditions and repeated during a head-out water immersion which increased ...
Arterial baroreceptors are mechanical sensors that detect blood pressure changes. It has long been suggested that the two arterial baroreceptors, aortic and carotid baroreceptors, have different pressure sensitivities. However, there is no consensus as to which of the arterial baroreceptors are more sensitive to changes in blood pressure. In the present study, we employed independent methods to compare the pressure sensitivity of the two arterial baroreceptors. Firstly, pressure-activated action potential firing was measured by whole-cell current clamp with a high-speed pressure clamp system in primary cultured baroreceptor neurons. The results show that aortic depressor neurons possessed a higher percentage of mechano-sensitive neurons. Furthermore, aortic baroreceptor neurons show a lower pressure threshold than that of carotid baroreceptor neurons. Secondly, uniaxial stretching of baroreceptor neurons, that mimics the forces exerted on blood vessels, elicited a larger increase in intracellular Ca2+
TY - JOUR. T1 - Carotid baroreceptor function in dogs with chronic norepinephrine infusion. AU - Wang, Jie. AU - Ochoa, Manuel. AU - Patel, Mrugesh B.. AU - Zucker, Irving H.. AU - Loud, Alden V.. AU - Zeballos, Guillermo A.. AU - Hintze, Thomas H.. PY - 1991/6. Y1 - 1991/6. N2 - Carotid baroreceptor function, the compliance of the carotid sinus wall, and the structure of the carotid artery were examined in dogs with elevated plasma norepinephrine (2, 000-4, 000 pg/ml) for 28 days. The dogs with high nonepinephrine were normotensive (100±4.0 versus 98±4.0 mm Hg; p,0.05) with bradycardia (65 ±4.0 versus 87 ±16 beats/m in; p,0.05) compared with normal dogs in the conscious state. However, after pentobarbital anesthesia blood pressure was significantly higher in dogs with chronic norepinephrine infusion (165±6 mm Hg) compared with normal dogs (132±6 mm Hg). To assess baroreceptor sensitivity, multiunit carotid baroreceptor activity was recorded from the right carotid sinus nerve, and the ...
Clinical trials on carotid receptor stimulation by an implantable device showed a significant reduction in both office systolic (22 or 34 mmHg) and diastolic (18 or 20 mmHg) blood pressure, 24-hour ambulatory blood pressure (14/9 mmHg), and heart rate (12 bpm), which was evident from study onset and was maintained at follow-up. Available data suggest a beneficial effect of carotid baroreceptor stimulation on the reversal of left ventricular hypertrophy and cardiac structure and function, with attenuated mitral A-valve velocity and reduced left atrial dimensions; also carotid baropacing does not impair the renal function of patients with resistant hypertension, even during prolonged follow-up periods (13-18).. ...
In this study, the vagal efferent arc was demonstrated to be unaffected by hypertension, with no difference in RR interval variation with respiration between the three groups. Furthermore, the Valsalva ratio was also similar between the three groups. Study of the baroreceptor-cardiac reflex, however, identified a consistent reduction in BRS with hypertension, irrespective of the method used for study (phase 4 of the Valsalva maneuver, phenylephrine pressor or SNP depressor method; Tables 2 and 3⇑⇑). BRS in the CH and ISH groups was significantly lower than in the NT group, but there were no differences between the two hypertensive groups. This observation is also borne out by the multiple regression analysis, which identified SBP as the single predictor of BRS, independent of age and DBP.. The present study is in agreement with that of Sumimoto et al,18 who found reduced BRS in elderly subjects (assessed only by the pressor method) categorized as having either diastolic hypertension ...
We examined the role of central mu- and delta-opioids on both neurohormonal responses and baroreceptor reflex in conscious rabbits. Both intracerebroventricular [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin, a mu-selective agonist, and [D-Ala2,D-Leu5]-enkephalin, a delta-selective agonist, caused dose-related increases in arterial pressure and renal sympathetic nerve activity, whereas intravenous injection of the same maximum dose of these peptides as that used in the intracerebroventricular experiment did not cause any cardiovascular and neuronal responses. On the other hand, increases in plasma epinephrine, norepinephrine, and glucose levels induced by intracerebroventricular [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin were significantly greater than those by [D-Ala2,D-Leu5]-enkephalin. Both enkephalins did not cause any responses in plasma renin activity, plasma vasopressin, and serum sodium and potassium concentrations. The sensitivity of the baroreceptor reflex control of renal sympathetic nerve activity ...
1. The carotid baroreceptors were stimulated for 2 min by neck suction at −30 and −60 mmHg in 19 normotensive subjects and 12 patients with moderate essential hypertension.. 2. Blood pressure was measured with a mercury sphygmomanometer and heart rate was derived from beat-to-beat analysis of the electrocardiogram. Blood flow was measured simultaneously at calf and finger with venous occlusion plethysmography and the vascular resistance was calculated.. 3. During neck suction at − 30 and − 60 mmHg there was a significant decrease in arterial blood pressure and heart rate. There was a transient vasodilatation of the calf blood vessels, while there was a sustained vasoconstriction of the finger blood vessels. These results were qualitatively similar in both groups; however, there were quantitative differences.. 4. These experiments show that there is a selective autonomic control of the different peripheral vascular beds by the carotid baroreceptors in both normotension and mild essential ...
... this image shows the pathway of the baroreceptor reflex the reflex that shares in the control of normal blood pressure showing: 1. aortic baroreceptor 2. aortic body 3. carotid sinus 4. carotid baroreceptor 5. inferior ganglion of vagus nerve for th
Recognition of drug-resistant hypertension has renewed enthusiasm for approaches based on devices and procedures. One promising therapy in-volves implanting a pulse generator (carotid baroreceptor activation), and another relies on applying radiofrequen-cy energy (renal sympathetic denervation). Reduction in blood pressure from carotid baroreceptor activation is a fundamental physiological response that was used to reset baroreflexes and control hypertension mainly in the late 1950s and 1960s. The introduction of antihypertensive drugs stopped further development of this approach until recently. A new device uses an implantable pulse generator, carotid sinus leads, and a programmer system that communicates with the implan-table pulse generator and allows for noninvasive programming and adjustments in the stimulation parameters.[17] Recent clinical trial results are encouraging. Patients with resistant hypertension on a median of five antihypertensive drugs experienced a 21/12 mm Hg reduction in ...
The complete arterial baroreceptor reflex pathway is a control system made up of two distinct portions as shown in Figure E-1: (1) an effector portion, including the heart and peripheral blood vessels, and (2) a neural portion, including the arterial baroreceptors, their afferent nerve fibers, the medullary cardiovascular centers, and the efferent sympathetic and parasympathetic fibers. Mean arterial pressure is the output of the effector portion and simultaneously the input to the neural portion. Similarly, the activity of the sympathetic (and parasympathetic) cardiovascular nerves is the output of the neural portion of the arterial baroreceptor control system and, at the same time, the input to the effector portion. For convenience, we omit continual reference to parasympathetic nerve activity in the following discussion. Throughout, however, an indicated change in sympathetic nerve activity should usually be taken to imply a reciprocal change in the activity of the cardiac parasympathetic ...
Afferent fibres from CNIX and CNX travel to the NTS in the medulla. Effector neurons from the RVLM are GABAergic and therefore inhibitory, i.e. increased baroreceptor discharge reduces tonic sympathetic tone and increases vagal tone.. Increased baroreceptor activity therefore results in:. ...
Looking for Baroreceptors? Find out information about Baroreceptors. sensory nerve terminals in blood vessels that perceive changes in blood pressure and reflexly regulate its level. Baroreceptors become stimulated when the... Explanation of Baroreceptors
TY - JOUR. T1 - Ketamine-mediated afferent-specific presynaptic transmission blocks in low-threshold and sex-specific subpopulation of myelinated ah-type baroreceptor neurons of rats. AU - Wang, Lu Qi. AU - Liu, Sheng Zhi. AU - Wen, Xin. AU - Wu, Di. AU - Yin, Lei. AU - Fan, Yao. AU - Wang, Ye. AU - Chen, Wei Ran. AU - Chen, Pei. AU - Liu, Yang. AU - Lu, Xiao Long. AU - Sun, Hong Li. AU - Shou, Weinian. AU - Qiao, Guo Fen. AU - Li, Bai Yan. PY - 2015/1/1. Y1 - 2015/1/1. N2 - Background: Ketamine enhances autonomic activity, and unmyelinated C-type baroreceptor afferents are more susceptible to be blocked by ketamine than myelinated A-types. However, the presynaptic transmission block in low-threshold and sex-specific myelinated Ah-type baroreceptor neurons (BRNs) is not elucidated. Methods: Action potentials (APs) and excitatory post-synaptic currents (EPSCs) were investigated in BRNs/barosensitive neurons identified by conduction velocity (CV), capsaicin-conjugated with Iberiotoxin-sensitivity ...
An increase in the internal diameter of an artery, triggered by vasomotor suppression, during the chemoreceptor response to decreased blood pressure.
In vagotomized and anesthetized rabbits, aortic pressure (AP), aortic depressor nerve activity (ANA), and renal sympathetic nerve activity (RNA) were simultaneously measured while perturbing AP randomly. To quantitatively characterize the role of the
Baroreceptors are sensory nerve endings in human blood vessels that detect blood pressure. There are two types of barorecptors...
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The carotid sinus baroreceptor reflex was studied in 11 normotensive subjects, using a variable pressure neck chamber and correcting for imperfect pressure transmission to the carotid sinus. Decreased carotid baroreceptor stimulation caused a sustaineded rise in arterial pressure, and increased carotid baroreceptor stimulation caused a sustain fall. The responses were in linear relation to the stimulus, and, after reaching the steady state, greater for the reduced than for the increased baroreceptor stimulation. Thus the carotid sinus baroreceptor reflex of the normotensive man is an effective antihypotensive and antihypertensive feedback system, though the former function may have more sensitivity. The increased and decreased baroreceptor stimulation by the neck chamber also caused bradycardia and tachycardia which were modest in magnitude and often transient. In eight subjects the reflex changes in heart rate induced by the neck chamber were compared with those induced by altering transmural ...
The goal of this study was to determine whether nitric oxide (NO) and the NO donor, S-nitrosocysteine (cysNO), modulate the activity of carotid sinus baroreceptors. Baroreceptor activity was recorded from the vascularly isolated carotid sinus in anesthetized rabbits. Baroreceptor activity decreased in a dose-dependent manner after injection of either NO or cysNO as constant pressure was maintained, and activity recovered spontaneously over time, within seconds to minutes. The baroreceptor pressure-activity relation was shifted significantly to the right by cysNO, with a profound suppression of activity at high pressure. Baroreceptor activity at 160 mm Hg averaged 76 +/- 8%, 60 +/- 6%, and 36 +/- 5% of the control maximum during exposure to 10(-4), 2 to 3 x 10(-4), and 10(-3) mol/L cysNO, respectively. The inhibition of activity by the L and D isomers of cysNO was equivalent and was blocked by reduced hemoglobin, suggesting that the effect was mediated by NO. The suppression of baroreceptor activity by
Baroreceptor activity and postural blood volume changes were evaluated in four normotensive and nine hypertensive uremic patients before and after bilateral nephrectomy. Baroreceptor activity, reflected by the slope of linear regression of R-R interval with drug-induced systolic blood pressure elevation, was significantly lower in hypertensive than in normotensive patients. Six of nine patients had normal blood pressure following bilateral nephrectomy; however, the mean slopes of all nine patients, irrespective of postnephrectomy blood pressure, approached that of normotensive uremic patients. The slopes of both normotensive and hypertensive patients, before and after bilateral nephrectomy, were significantly less than normal controls. Similar results were found in lowering blood pressure with amyl nitrite.. Depressed baroreceptor activity is suggested to be secondary to neuropathy of the autonomic nervous system, chronic hypertension, heart disease, and anemia. It is speculated that this ...
In hypertension baroreceptor-mediated modulation of heart rate is impaired, resulting in a decreased vagal control. Reactive oxygen species produced locally in the vasculature decrease baroreceptor sensitivity. Folic acid has antioxidant properties. Therefore, the aim of this study was to test whether folic acid improves baroreceptor function in hypertension. Twenty-one male patients with hypertension not taking any drugs for 2 weeks participated in the study and were randomized to folic acid 5 mg or matching placebo. Cardiac and vascular sympathetic baroreceptor functions were tested before and after a single dose of folic acid or placebo with two different methods: the alpha-coefficient method and the phenylephrine (PE) and sodium nitroprusside (SNP) bolus method. In the folic acid group both methods showed significantly improved cardiac and vascular sympathetic baroreceptor sensitivity compared with placebo. This study provides evidence that folic acid improves cardiac and vascular ...
TY - JOUR. T1 - Cellular and Molecular Mechanisms Underlying Arterial Baroreceptor Remodeling in Cardiovascular Diseases and Diabetes. AU - Tu, Huiyin. AU - Zhang, Dongze. AU - Li, Yu Long. PY - 2019/2/1. Y1 - 2019/2/1. N2 - Clinical trials and animal experimental studies have demonstrated an association of arterial baroreflex impairment with the prognosis and mortality of cardiovascular diseases and diabetes. As a primary part of the arterial baroreflex arc, the pressure sensitivity of arterial baroreceptors is blunted and involved in arterial baroreflex dysfunction in cardiovascular diseases and diabetes. Changes in the arterial vascular walls, mechanosensitive ion channels, and voltage-gated ion channels contribute to the attenuation of arterial baroreceptor sensitivity. Some endogenous substances (such as angiotensin II and superoxide anion) can modulate these morphological and functional alterations through intracellular signaling pathways in impaired arterial baroreceptors. Arterial ...
Carotid sinus reflex interactions were studied in 10 dogs anesthetized with pentobarbital sodium. The right and left carotid sinus regions were isolated and perfused at controlled pressures. Pressure in the right and left carotid sinuses were independently varied, and the resulting steady-state reflex changes in arterial pressure, heart rate, respiratory frequency, tidal volume, and total ventilation were measured. Reflex changes when carotid sinus pressure was changed on one side were strongly influenced by pressure in the contralateral carotid sinus (P less than 0.05). Right carotid sinus gain was found to be 0.628 +/- 0.058 at a left carotid sinus pressure of 50 mmHg and 0.148 +/- 0.027 when left carotid sinus pressure was 200 mmHg. Similar results were found for left carotid sinus gain. Suppression was also found for heart rate, respiratory rate, tidal volume, and total ventilation. The hypothesis that rapid resetting of one carotid sinus baroreflex might influence responses from the other ...
TY - JOUR. T1 - Excitatory inputs to the RVLM in the context of the baroreceptor reflex. AU - Sved, Alan F.. AU - Ito, Satoru. AU - Madden, Christopher (Chris). AU - Stocker, Sean D.. AU - Yajima, Yoshiharu. PY - 2001. Y1 - 2001. N2 - The central neural circuit mediating baroreceptor control of sympathetic vasomotor outflow involves an excitatory projection from arterial baroreceptors to nucleus tractus solitarius, an excitatory projection from nucleus tractus solitarius to the caudal ventrolateral medulla, an inhibitory projection from the caudal ventrolateral medulla to the rostral ventrolateral medulla (RVLM), and an excitatory projection from the RVLM to sympathetic preganglionic neurons in the spinal cord. For this circuit to be operational, the relevant neurons in the RVLM must be tonically active. Indeed, numerous studies have demonstrated that RVLM vasomotor neurons are tonically active; however, little is known regarding the nature of the tonic excitatory drive to these neurons. We ...
Diabetes mellitus (DM) is a disease of increasing incidence and prevalence. Arterial baroreceptors are stretch-sensitive receptors, which in a reflex manner are involved in the homeostatic control of arterial blood pressure. Diabetic subjects have depressed baroreflex sensitivity (BRS), although the exact pathomechanisms are unclear. In this review, we discuss the features, clinicaland prognostic implications of reduced BRS for diabetic patients and the potential involvement of cardiovascular autonomic neuropathy and atherosclerosis. Finally, we demonstrate evidence on interventions (e.g. pioglitazone, alpha-lipoic acid, leptin, fluvastatin, physicaltraining etc.) which could improve BRS and ameliorate cardiovascular autonomic dysfunction in diabetic patients ...
PJ Counihan, GA Haywood, AC ODonoghue, WJ McKenna; Abnormal Baroreceptor Sensitivity in Hypertrophic Cardiomyopathy. Clin Sci (Lond) 1 October 1990; 79 (s23): 13P. doi: https://doi.org/10.1042/cs079013Pb. Download citation file:. ...
Disappearance rates of intracisternally administered 3H-norepinephrine and activities of tyrosine hydroxylase were examined in the rabbit in five brain regions (telencephalon, hypothalamus, midbrain, medulla-pons, and cerebellum) and in three cord regions (cervical, thoracolumbar, and lumbosacral) 2 weeks after section of the carotid sinus and aortic nerves. Mean blood pressure rose by 29% and heart rate by 17% in the animals with neurogenic hypertension. Endogenous catecholamine concentrations in the eight regions examined were not altered by denervation. In the thoracolumbar region of the spinal cord, 3H-norepinephrine turnover and tyrosine hydroxylase activity were increased approximately twofold in hypertensive rabbits. We suggest that these changes reflect increased physiological activity of bulbospinal noradrenergic neurons and that this increase may mediate the rise in arterial pressure or heart rate that follows sinoaortic denervation. The turnover of 3H-norepinephrine increased in the ...
Looking for online definition of Pressoreceptors in the Medical Dictionary? Pressoreceptors explanation free. What is Pressoreceptors? Meaning of Pressoreceptors medical term. What does Pressoreceptors mean?
The major new finding of this study is the evidence that systemic BP changes are important determinants of peripheral sympathetic nerve control and HR response during dobutamine infusion. In young controls, dobutamine infusion markedly increased BP, which activated the arterial baroreceptors leading to subsequent inhibition of MSNA, as well as to limitation in the increase in HR. In contrast, the BP response to dobutamine was much less marked in the matched controls and, in the absence of arterial baroreceptor activation, dobutamine infusion did not change MSNA and did not limit the increase in HR. These findings are important as they may account for variations in the HR responses among subjects during dobutamine stress testing.. The response in the patients with severe CHF was similar to that observed in the matched controls, with no elevation in MBP and no changes in MSNA. The lack of increase in HR could be explained by the marked beta-adrenergic downregulation in end-stage HF (14). Resting ...
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He obtained his Ph.D. degree in 2004 on baroreceptor reflex function in neonates from the University of Maastricht. His major research interests are patient monitoring, integrative physiology and long-term follow-up of extremely preterm infants.. From 2002 onwards he co-supervises master and PhD students of the Eindhoven University of Technology, who carry out research projects in the neonatal intensive care unit of Máxima MC in close collaboration with the Department of Clinical Physics. Between 2014-2019 he was involved as co-supervisor in several of the IMPULS II PhD projects on neonatal monitoring. From 2018 he is involved as co-supervisor in ALARM (project leader dr. ir. Carola van Pul), the project on Alarm Limiting and Algorithm-based Monitoring. Since 2018 he is project leader of the EPIDAF (Extremely Preterm Infants - Dutch Analysis on Follow-up) study, a national study on outcome in extremely preterm infants. ...
Recent technologic advances rekindled interventional management of resistant hypertension, either by carotid. baroreceptor activation or renal sympathetic denervation. Interventional techniques result in impressive falls in office blood pressure (BP); however, ambulatory BP reductions are rather modest. This disparity between office and ambulatory BP reductions is observed with antihypertensive drugs, but at a much lower degree. Available explanations are not convincing, therefore, we propose that sympathetic overactivity may partially explain this divergence. Further studies are needed to prove or disprove our hypothesis.. ...
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For the past week I have been fighting off what I thought was a sinus infection (sinus pressure, drainage, plugged up ears, headache, and an off/on fever). Starting about two or three days ago the fev...
TY - JOUR. T1 - Aortic depressor nerve stimulation does not impede the dynamic characteristics of the carotid sinus baroreflex in normotensive or spontaneously hypertensive rats. AU - Kawada, Toru. AU - Turner, Michael J.. AU - Shimizu, Shuji. AU - Fukumitsu, Masafumi. AU - Kamiya, Atsunori. AU - Sugimachi, Masaru. PY - 2017/5/30. Y1 - 2017/5/30. N2 - Recent clinical trials in patients with drug-resistant hypertension indicate that electrical activation of the carotid sinus baroreflex (baroreflex activation therapy) can reduce arterial pressure (AP) for more than a year. To examine whether the electrical stimulation from one baroreflex system impedes normal short-term AP regulation via another unstimulated baroreflex system, we electrically stimulated the left aortic depressor nerve (ADN) while estimating the dynamic characteristics of the carotid sinus baroreflex in anesthetized normotensive Wistar-Kyoto (WKY, n=8) rats and spontaneously hypertensive rats (SHR, n=7). Isolated carotid sinus ...
In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage. The carotid sinus extends from the bifurcation to the "true" internal carotid artery. The carotid sinus is sensitive to pressure changes in the arterial blood at this level. It is the major baroreception site in humans and most mammals. The carotid sinus is the reflex area of the carotid artery, consisting of various nerve receptors for baroregulation (pressure regulation of the body in sync to external conditions). The carotid sinus contains numerous baroreceptors which function as a "sampling area" for many homeostatic mechanisms for maintaining blood pressure. The carotid sinus baroreceptors are innervated by the sinus nerve of Hering, which is a branch of cranial nerve IX (glossopharyngeal nerve). The glossopharyngeal nerve synapses in the nucleus tractus ...
1. Carotid baroreceptor manipulation (neckchamber technique) and passive head-up tilting were used in ten patients with renovascular hypertension and in five subjects with essential hypertension under diuretic treatment to study reflex control of renin secretion" at high basal-renin production rates.. 2. Reflex effects of carotid baroreceptor manipulation on renin secretion were only minor. During baroreceptor deactivation there was a moderate increase in mean arterial pressure, but an inconsistent change in the renal venous-arterial difference in plasma renin activity (PRA).. 3. During baroreceptor stimulation there was a modest fall in mean arterial pressure and a marked rise in the renal venous-arterial difference in PRA. This was opposite to the fall which might have been predicted as a result of the sympathetic depressor influence of the baroreceptor stimulus. Conversely, tilting increased the venous-arterial PRA difference by about 200%.. 4. It is concluded that when renin production rate ...
The goal of the present study was to determine whether oxygen-derived free radicals contribute to baroreceptor dysfunction in atherosclerosis. Baroreceptor activity was measured from the carotid sinus nerve during pressure ramps in isolated carotid sinuses of anesthetized rabbits. Rabbits fed a 0.5% to 1.0% cholesterol diet for 7.9 +/- 0.4 months (mean +/- SE; range, 5.5 to 10) developed atherosclerotic lesions in the carotid sinuses. Maximum baroreceptor activity measured at 140 mm Hg and the slope of the pressure-activity curve were reduced in atherosclerotic (n = 15) compared with normal (n = 13) rabbits (425 +/- 34 versus 721 +/- 30 spikes per second and 6.2 +/- 0.6 versus 10.8 +/- 0.8 spikes per second per mm Hg, respectively, P | .05). The level of activity was inversely related to plasma cholesterol concentration (r = .86, P | .001) and total cholesterol load (plasma concentration x duration of diet, r = .92). Mean arterial pressure was normal in both groups. Exposure of the carotid sinus to the
TY - JOUR. T1 - Treating resistant hypertension now and in the future. AU - Sata, Yusuke. AU - Xu, Jianzhong. AU - Hering, Dagmara. AU - Schlaich, Markus. PY - 2013. Y1 - 2013. N2 - Treatment of resistant hypertension is a priority because patients with nonoptimal blood pressure are at high risk for major cardiovascular events. Pharmacological advances include the use of aldosterone antagonists and the development of several new strategies. Device-based therapies such as catheter-based renal denervation and electrical stimulation of baroreceptors are showing promising results.. AB - Treatment of resistant hypertension is a priority because patients with nonoptimal blood pressure are at high risk for major cardiovascular events. Pharmacological advances include the use of aldosterone antagonists and the development of several new strategies. Device-based therapies such as catheter-based renal denervation and electrical stimulation of baroreceptors are showing promising results.. UR - ...
An implantable device (20) uses the carotid baroreflex in order to control systemic blood pressure. The implant includes sampling and pulse stimulation electrodes (44) preferably located on the carotid sinus nerve branch of the glossopharyngeal nerve, adjacent and distal to the carotid sinus baroreceptors. The stimulators have an external control unit, which communicates with the implant for determining appropriate operational parameters, and for retrieving telemetry information from the devices data bank. Typically two internal devices are implanted, one at each side of the patients neck.
The results from these studies demonstrate that afferent input from peripheral chemoreceptors and mechanoreceptors contributes little to the systemic hemodynamic and sympathetic responses after term delivery by cesarean section. Furthermore, birth-related increases in circulating norepinephrine but not epinephrine appear dependent on afferent input from the carotid sinus or aortic depressor nerves, which carry both chemo- and baroreceptor afferents from the carotid sinus and aortic arch, respectively. Finally, we observed that vagal afferent activity regulates basal fetal plasma ANG II levels and exerts a tonic inhibitory effect on AVP release after birth.. Both peripheral chemoreceptors and baroreceptors have been shown to be functional during fetal life. The fetal cardiovascular response to acute hypoxemia is well described, consisting of a decrease in heart rate and increase in peripheral vascular resistance (7). Carotid denervation abolishes these responses to hypoxemia and NaCN, a chemical ...
It is well known that the sensitivity of the reflex control of HR in response to vasoactive agents is altered independently by hypertension and by aging in both animal models (27), and in human subjects (22, 26, 49). A consequence of both hypertension and aging is a reduction in vascular distensibility, although the mechanisms are not identical. The demonstration that reduced baroreceptor sensitivity could be accounted for by reduced aortic compliance observed in both aged normotensive rats (5) and hypertensive rats (51), as discussed in the previous section, may provide an explanation for the decreased baroreflex control of HR in hypertensive subjects and aged normotensive humans.. For example, Monahan et al. (43) measured baroreflex control of HR and carotid compliance in 47 healthy sedentary men ranging from 19 to 76 years of age. Monahan and colleagues reported a progressive decline in baroreflex sensitivity with increasing age. The decline in baroreflex sensitivity correlated significantly ...
Adaptive servoventiation therapy (ASV) is designed to treat hypocapnic central sleep apnoea (Cheyne-Stokes respiration) in heart failure (HF) . It remains unclear whether this therapy increases stroke volume (SV) and if, this is mediated by a decrease in cardiac afterload due to increased parasympathetic nervous activity (PNA) or by a change in baroreceptor reflex sensitivity.. 12 patients with HF (12 male; 70 ± 9 years; NYHA ≥ II; EF ≤ 45% and Cheyne- Stokes respiration) and 14 healthy volunteers (13 male, 24 ± 4 years, EF ≥ 60%, AHI , 5/h) were ventilated non-invasively for 1 h with ASV (PaceWave™). Hemodynamic effects were analyzed non-invasively and compared to findings 30 min before and after ASV.. Changes in SV on ASV were significantly different between both groups (+5 ± 8% in HF patients vs. -4 ± 9% in volunteers, p=0.01). HF demonstrated a significant increase in markers of PNA (HFnuRRI) during ASV (56 ± 21 % vs. 68 ± 20 % on ASV; p=0.02), whereas volunteers showed a shift ...
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People 60 and older dont need to be treated as aggressively for high blood pressure, according to new physician guidelines that may help lower the number of medicines taken by baby boomers.
Guideliner should be advanced all the way into the coronary artery over the Rota sheath/burr, then forcefully pull the burr. Other approach could be tried is to advance the another guide Cather by additional access and try to advance a guidewire and a small balloon alongside the burr; If successful then gradually dilate with PTCA balloon at the level of stuck burr which will then allow burr to become free and to be pulled out safely. We have tried this approach 3 times in the past and always failed to advance the guidewire alongside the burr as burr is deeply entrapped in the artery. If all these maneuvers still fails, then last option will be to send pt for CT surgery to remove the burr openly.. ...
Arterial baroreceptors in the carotid sinus (CBR) and aortic arch (ABR) regions exert important control over heart rate and peripheral vascular responses to changes in arterial pressure. The relative roles of these two baroreflex pathways on control of sympathetic nerve activity during sustained elevation of arterial pressure in man is unknown. We therefore studied the relative contributions of the carotid versus the aortic baroreflexes on the control of muscle sympathetic nerve activity (MSNA) during elevation of arterial pressure in normal human subjects. In eight normal men (group I), we measured MSNA (microneurography) during sustained elevation of arterial pressure produced by intravenous infusion of phenylephrine (PE) alone (combined ABR and CBR activation) versus during PE infusion with superimposed application of sustained external neck pressure (NP). NP was applied during sustained PE infusion to eliminate the increase in transmural carotid sinus pressure and thus remove CBR activation, ...
The baroreflex or baroreceptor reflex is one of the bodys homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure reflexively causes the heart rate to decrease and also causes blood pressure to decrease. Decreased blood pressure decreases baroreflex activation and causes heart rate to increase and to restore blood pressure levels. The baroreflex can begin to act in less than the duration of a cardiac cycle (fractions of a second) and thus baroreflex adjustments are key factors in dealing with postural hypotension, the tendency for blood pressure to decrease on standing due to gravity. The system relies on specialized neurons, known as baroreceptors, in the aortic arch, carotid sinuses, and elsewhere to monitor changes in blood pressure and relay them to the Medulla. Baroreceptors are stretch receptors and respond to the pressure induced stretching of the blood vessel in ...
There are four main sinus cavities in the body. They are located on either side of the nose, behind and in-between the eyes, and in the forehead. Each sinus cavity has an opening into the nose for the exchange of air and mucous. When the cavities get filled with mucous it creates a perfect breeding ground for bacteria.. Some of the most common sinus pressure symptoms include severe nasal congestion and yellowish green discharge which is thick because it contains pus. Pain in the teeth is also very normal. This pain increases when you bend over. Symptoms may vary however, depending on the sinuses involved.. Sinus pressure symptoms normally occur for about ten days and they may carry on for a longer period if a cold or flu occurs. They normally worsen after five to seven days. In some cases fever also occurs. Fever is more common in children than in adults therefore it is not a very reliable way of diagnosing sinus pressure.. Far more severe sinus pressure symptoms are terrible headaches, pain or ...
The use of baroreflex stimulation devices (also known as baroreflex activation therapy) is a potential alternative treatment for resistant hypertension and heart failure. Both hypertension and heart failure are relatively common conditions and are initially treated with medications and lifestyle changes. A substantial portion of patients are unresponsive to conventional therapy and treating these patients is often challenging and can lead to high costs and adverse effects. As a result, there is a large unmet need for additional treatments.. New treatment options are being explored to treat drug-resistant hypertension. One such approach is the electrical activation of the carotid sinus baroreflex. Baroreceptors are pressure sensors contained within the walls of the carotid arteries. They are part of the autonomic nervous system that regulates basic physiologic functions such as heart rate and blood pressure (BP). When these receptors are stretched, as occurs with increases in BP, the baroreflex ...